Two-photon excitation and ionization of inner atomic shells

The spectrum of platinum is studied in the region from 250 to 1250 Å. The twenty-two 5d6s-5d6p spectral lines of the PtIX are assigned. All levels of the 5d6s configuration are found. The assignment of the previously known 5d6p levels is confirmed and their positions are refined. The 5d ², 5d6s, and 5d6p configurations are theoretically described by the method of orthogonal operators. These calculations are compared with the data obtained by a conventional method using the Cowan program.     

Nonradiative decay from 5d states of rare earths in crystals

Nonradiative decay from 4f^n?1 5d states was investigated for trivalent rare earths in Y₃Al₅O₁₂. The rates of both 5d→4f and 5d→5d transitions were determined from measurements of the lifetimes and intensities of 5d fluorescence from Ce³⁺ and Pr³⁺. Because of the stronger ion-lattice coupling, nonradiative decay rates for transitions involving 5d states are much faster than those between 4f states. Decay rates are dependent upon the temperature and the energy gap to the next-lower level. The temperature dependences of the 5d fluorescence lifetimes from 77 to 700°K are reported.     

High-lying odd configurations of quintuply ionized bismuth (Bi VI)

The spectrum of Bi VI in a wavelength region of 177–431 Å was studied. The transitions from the levels of the interacting configurations 5d ⁸6s6p+5d ⁹7p+5d ⁹5f+5d ⁹6f to the levels of the 5d ¹⁰ and 5d ⁹6s configurations were analyzed. 174 spectral lines were identified, and 79 new levels of high-lying odd configurations of Bi VI were found.     

Radiative constants in the spectra of ions of the krypton isoelectronic sequence

The probabilities of the 4p ⁶,4p ⁵5p→4p ⁵(4d+5s) radiative transitions and the radiative lifetimes of the 4p ⁵4d,4p ⁵5s, and 4p ⁵5p levels are calculated semiempirically for the RbII-MoVII isoelectronic sequence.     

Absolute transition probabilities of Xe(I) visible lines

Absolute transition probabilities of (5p⁵6s-6p⁵6p¹) and (5p⁵6s-5p⁵7p) xenon lines have been measured in emission in a conventional shock tube. The method of data collection and reduction enables optical depth compensation to be made in a straightforward way. Results are compared with theoretical and with other experimental data.     

Termanalyse der 4d 9 5s 5d-Konfiguration im Bogenspektrum des Silbers

The arc spectrum of silver has been remeasured in the range of 1100 to 9800 Å. This yielded some 140 new lines. Analysing these lines together with about 50 previously unidentified lines of Shenstone established 20 new levels. The configurations 4d ⁹ 5s 5p and 4d ⁹ 5s 6s are now completely analysed. In the 4d ⁹ 5s 5d-configuration about half of the expected levels were identified. Two new 4d ⁹ 5s 7s levels were found.     

Spectroscopy and Photophysics of Monomethyl-Substituted Derivatives of 5-Deazaalloxazine and 10-Ethyl-5-Deaza-Isoalloxazine

Steady-state and time-resolved spectra were used to describe the singlet and triplet states of 8-methyl-5-deazaalloxazine (8-Me-5-DAll), 9-methyl-5-deazaalloxazine (9-Me-5-DAll) and 10-ethyl-5-deaza-isoalloxazine (10-Et-5-DIAll). Solvatochromic properties were described using different polarity scales, including Δf and the four-parameter scale proposed by Catalán. The results indicate that the Catalán scale shows a strong influence of solvent acidity (hydrogen-bond donating ability) on the emission properties of 8-Me-5-DAll and 9-Me-5-DAll. These results indicate the importance of intermolecular solute-solvent hydrogen-bonding interactions in the excited state of these compounds. Contrary to deazaalloxazines, solvent acidity affects the absorption spectra of 10-Et-5-DIAll. Fluorescence lifetimes and quantum yields and also transient absorption spectra were determined for all of the compounds studied. Electronic structure and S ₀ -S _i , S ₀ -T _i , T ₁ -T _i transitions energies and oscillator strengths were calculated using the TD-DFT methods. Theoretical calculations were compared to experimental data.     

Influence of Yb concentration on upconversion luminescence of Ho

Upconversion (UC) emissions at 360 ((⁵F, ³F, ⁵G)₂ → ⁵I₈), 392 (³K₇/⁵G₄ → ⁵I₈), 428 (⁵G₅ → ⁵I₈), 554 (⁵S₂/⁵F₄ → ⁵I₈), 667 (⁵F₅ → ⁵I₈) and 754 (⁵S₂/⁵F₄ → ⁵I₇) nm were obtained in 0.1 mol% Ho³⁺/x mol% Yb³⁺:Y₂O₃ (x = 2, 5, 8, 11, 15) bulk ceramics under infrared (IR) excitation at 976 nm. The intensity of the UC luminescence centered at 554 and 754 nm increased with Yb³⁺ concentration from 2 to 5 mol% and decreased from 5 to 15 mol%, while the UC luminescence centered at 392, 428 and 667 nm increased with Yb³⁺ concentration from 2 to 11 mol%, then started to reduce with Yb³⁺ concentration until 15 mol%. This comes from the competition between the energy back transfer (EBT) process [⁵S₂/⁵F₄(Ho) + ²F_7/2(Yb) → ⁵I₆(Ho) + ²F_5/2(Yb) as well as ⁵F₅(Ho) + ²F_7/2(Yb) → ⁵I₇(Ho) + ²F_5/2(Yb)] and spontaneous radiation process. The intensity of the UC luminescence centered at 360 nm always increases with Yb³⁺ concentration from 2 to 15 mol%. We believe that it may come from the cooperation of energy transfer process from Yb³⁺ ions in the ²F_5/2 state and the cross energy transfer process ⁵S₂/⁵F₄ + ⁵I₆ → (⁵F, ³F, ⁵G)₂ + ⁵I₈.     

Mid-infrared emissions from Ho3+ in Ga2S3-GeS2-Sb2S3 glass

Emission properties were investigated in the infrared region for Ga₂S₃-GeS₂-Sb₂S₃ glasses doped with Ho³⁺. We performed Judd–Ofelt analysis and lifetime measurements of the ⁵I₄, ⁵I₅, and ⁵I₆ levels, which are the initial levels of the mid-infrared emissions between 3 to 5 μm of Ho³⁺. The quantum efficiencies reached approximately 18%, 64%, and ～100% for the ⁵I₄, ⁵I₅, and ⁵I₆, respectively. Population analyses were carried out from the relative intensities of the emissions in the near-infrared region. We investigated the dependences on the Ho³⁺ ion concentration of the population ratio of the initial levels to the final levels, [initial]/[final], of the mid-infrared emissions. The population ratio of [⁵I₅]/[⁵I₆] decreased with increase of the Ho³⁺ concentration while those of [⁵I₄]/[⁵I₅] and [⁵I₆]/[⁵I₇] increased. Particularly, the former, [⁵I₄]/[⁵I₅], rapidly increased because of the strong concentration quenching of the ⁵I₅ level through cross relaxation. It was found that the population inversion for the 4.8 μm emission due to the transition, ⁵I₄→⁵I₅, was achieved at high Ho³⁺ concentration in the present experiments.     

Hyperfine structure measurements in the ground states5 F 5,5 F 4,5 F 3 and5F2 of99Ru and101Ru with the atomic beam magnetic resonance method

The hyperfine structure of the four lowest levels⁵ F _{5, 4, 3, 2} of the⁵ F ground state multiplet arising from the configuration 4d ⁷ 5s in⁹⁹Ru and¹⁰¹Ru has been studied by the atomic — beam magnetic — resonance technique. After applying corrections due to the effects of off-diagonal hyperfine mixing we obtain the following multipole interaction constants:⁹⁹Ru:A(⁵ F ₅)=?204.5514(33) MHzB(⁵ F ₅)=27.281 (62) MHzA ⁵ F ₄=?163.6845(36) MHzB(⁵ F ₄)=17.455(52) MHzA ⁵ F ₃=?135.0294(37) MHzB(⁵ F ₃)=10.164(50) MHzA(⁵ F ₂)=? 82.5325(27) MHzB(⁵ F ₂)=5.457(22) MHz¹⁰¹Ru:A(⁵ F ₅)=?229.2881(33) MHzB(⁵ F ₅)=158.934(62) MHzA(⁵ F ₄)=?183.4744(36) MHzB(⁵ F ₄)=101.799(52) MHzA(⁵ F ₃)=?151.3502(38) MHzB(⁵ F ₃)=59.323(50) MHzA(⁵ F ₂)=?92.4974(27) MHzB(⁵ F ₂)=31.869(23) MHz. The magnetic dipole and the electric quadrupole moments of the⁹⁹Ru and¹⁰¹Ru nuclear ground states as calculated from these constants are the following:μ _I (⁹⁹Ru)=?0.594(119) nmQ(⁹⁹Ru)=0.077 (15) barnsμ _I (¹⁰¹Ru)=?0.666(133)nmQ(¹⁰¹Ru)=0.45 (9) barns. From measurements of the Zeeman effect in the even isotope¹⁰²Ru we find the followingg _J -factors for the⁵ F ground multiplet:g _J (⁵ F ₅)=1.397741(20)g _J (⁵ F ₄)=1.347604(20)g _J (⁵ F ₃)=1.248988(20)g _J (⁵ F ₂)=1.001120(3).     

Measurement of the nuclear quadrupole moment of53Cr by laser-Rf double resonance

The hyperfine structure of the metastable atomic states (3d ⁴4s ²)⁵ D _1,2,3,4 of⁵³Cr has been measured using theABMR-LIRF method (atomic beam magnetic resonance detected by laser induced resonance fluorescence). The dipole coupling constantsA and the quadrupole coupling constantsB are found to beA(⁵ D ₁)=?17.624(2) MHzB(⁵ D ₁)=?21.847(5) MHzA(⁵ D ₂)=?25.113(2) MHzB(⁵ D ₂)=?13.485(5) MHzA(⁵ D ₃)=?35.683(2) MHzB(⁵ D ₃)=15.565(5) MHzA(⁵ D ₄)=?48.755(2) MHzB(⁵ D ₄)=63.021(5) MHz. From these measured hfs constants the electric quadrupole moment for⁵³Cr is calculated to beQ=?0.15 (5) barn. The 30% error takes into account the uncertainties due to configuration interaction effects (shielding and antishielding effects) and of deviations from pure SL-coupling for the states⁵ D _1,2,3,4.     

High-contrast atomic dark resonances formed in a ladder system of rubidium atoms in submicron structures

It is shown that high-contrast resonance of electromagnetically induced transparency (EIT) in a ladder Ξ-system of 5S _1/2-5P _3/2-5D _5/2 levels can be formed in optical cells containing a column of rubidium vapor with thickness L in an interval of 100 nm ≤ L ≤ 780 nm. Using bichromatic laser radiation with certain parameters, an 83% contrast of the EIT resonance (or dark resonance, DR) has been achieved for a vapor column thickness of L = 780 nm. An important condition for the formation of high-contrast DR is that the frequency of the coupling laser radiation must be resonant with the frequency of the corresponding 5P _3/2-5D _5/2 transition (for the probe radiation frequency scanned over the 5S _1/2-5P _3/2 transition). It is also shown that a DR can be formed at a record small vapor column thickness of L ≈ 100 nm. Expressions that can be used to estimate the expected DR width at small L values are presented.     

The probabilities of radiative transitions and lifetimes of levels in the spectra of Cu XX,La IV

The probabilities of radiative electric dipole transitions 2p ⁵3p, 2p ⁶–2p ⁵3s, and 2p ⁵3d in the spectrum of neon-like copper Cu XX and 5p ⁵6p, 5p ⁶–5p ⁵6s, 5p ⁵7s, and 5p ⁵5d in the spectrum of xenon-like lanthanum La IV are calculated. The wave functions of the intermediate coupling were found from the wellknown experimental energy levels by the least-squares method (LSM). To transfer to an absolute scale the radial integrals for the transitions calculated in the form of a length on the Hartree–Fock functions have been used. By summing the calculated probabilities of the transitions, the lifetimes of the levels of configurations 2p ⁵3s, 2p ⁵3p, and 2p ⁵3d in the spectrum of Cu XX and levels of configurations 5p ⁵6s, 5p ⁵6p, and 5p ⁵7s in the spectrum of La IV have been obtained.     

Hyperfine anomaly in the spectrum of the osmium atom. effect of the spatial distribution of nuclear charge

Contributions of the superposition of configurations ns ²5d ⁸+ns5d ⁸ n′s (n=1–5, n′=6–10) and ns ²5d ⁶+ns5d ⁶ n′s (n=1–6, n′=7–10) to parameters a _5d ⁰¹ , a _5d ¹² , and a _5d ¹⁰ of the hyperfine structure in the spectrum of the osmium atom OsI are calculated. It is shown that the nonzero contribution is made only to a _5d ¹⁰ . The effect of the spatial distribution of nuclear charge on the parameters of the hyperfine structure in the spectra of ¹⁸⁷Os and ¹⁸⁹Os isotopes and on the hyperfine anomaly for the 5d ⁷6s levels in the spectrum of these isotopes is estimated.     

Investigation of the ν5 band of methylacetylene by infrared laser Stark and microwave spectroscopy

Microwave spectra have been studied in the ground and v₅ = 1 (CC stretching mode) states of methylacetylene. From these data, dipole moments and rotational and centrifugal distortion constants have been determined, as follows: μ_D⁽⁰⁾ = 0.7839 ± 0.0010 D, μ_D⁽⁵⁾ = 0.7954 ± 0.0010 D, B₅ = 8508.119 ± 0.003 MHz, D_J⁽⁵⁾ = 1.8 ± 0.2 kHz, and D_JK⁽⁵⁾ = 169 ± 1 kHz. Laser Stark spectra have been obtained for the ν₅ band of this molecule and from these spectra the following vibration-rotation parameters have been determined: ν₅⁰ = 93.27540 ± 0.00007 cm^?1, A₅ - A₀ = ?227.0 ± 2.3 MHz and D_K⁽⁵⁾ - D_K⁽⁰⁾ = ?0.05 ± 0.50 MHz. The higher-J and -K states of the v₅ = 1 state appear to be purturbed.     

Vibrational study of layered ZnPS3 compounds intercalated with [Co(η5 -C5H5)2+] and [Cr(η6 -C6H6)2+] CATIONS

Infrared and Raman spectra (10–3100 cm^?1) of the layered ZnPSs compound and of intercalates with [Co(η⁵ ? C₅H₅)₂⁺] and [Cr(η⁶ ? C₆H₆)₂⁺] cations in the polycrystalline state have been recorded 300–10 K temperature range. A complete assignment of the spectra is proposed in terms of PSs group motions, Zn²⁺ ion translations and [Co(η⁵ ? C₅H₅)₂⁺] or [Cr(η⁶ ? C₆H₆)₂⁺] internal vibrations. New low frequency for the [Co(η⁵-C₅H₅)₂⁺] intercalate at low temperature are assigned to librational and torsional modes of C₅H₅ rings. Moreover, the preresonance Raman spectra of this intercalate show a selective enhancement for the metal-ligand vibrations when the charge transfer band of the cobalticenium is approached. One concludes that guest molecules are intercalated under their cationic form, are weakly interacting with the host lattice and seem to be dynamically disordered at room temperature.     

Original magnetic behaviour observed in RNi5−xCux alloys (R = Pr,Gd or Y)

The Curie temperatures, spontaneous magnetizations and initial susceptibilities were investigated in the temperature interval from 1.5 to 40 K for the pseudobinary alloys RNi_5−xCu_x, where R = Pr, Gd and Y, x ≤ 2.6. It was discovered that the solid solutions PrNi_5−xCu_x between the PrNi₅ and PrCu₅ Van Vleck paramagnets are ferromagnets for intermediate Cu concentrations. It was shown that the ferromagnetic ordering in PrNi_5−xCu_x alloys can be explained by concentrational enhancement of 3d band susceptibility which in its turn leads to the enhancement of f-f exchange interactions. The maxima on the concentration dependences of both Curie temperatures for the RNi_5−xCu_x ferromagnets with R = Pr, Gd and susceptibility for the YNi_5−xCu_x Pauli paramagnets are manifestations of 3d band magnetism.     

Structure,electronic and magnetic properties of hexagonal boron nitride sheets doped by 5d transition metal atoms: First-principles calculations and molecular orbital analysis

A first-principles calculation based on density functional theory is carried out to reveal the geometry, electronic structures and magnetic properties of hexagonal boron nitride sheets (h-BNSs) doped by 5d transitional mental atoms (Lu, Hf, Ta, W, Re, Os, Ir, Pt, Au and Hg) at boron-site (B_5d) and nitrogen-site (N_5d). Results of pure h-BNS, h-BNS with B vacancy (V_B) and N vacancy (V_N) are also given for comparison. It is shown that all the h-BNSs doped with 5d atoms possess a C_3v local symmetry except for N_Lu and N_Hg which have a clear deviation. For the same 5d dopant, the binding energy of B_5d is larger than that of N_5d, which indicates the substitution of a 5d atom for B is preferred. The total densities of states are presented, where impurity energy levels exist. Besides, the total magnetic moments (TMMs) change regularly with the increment of the 5d atomic number. Theoretical analyses by molecular orbital under C_3v symmetry explain the impurity energy levels and TMMs.     

Role of electron correlation effects in δ-Pu and “115”-Pu-based unconventional superconductors

Electronic structure calculations combining the local density approximation with an exact diagonalization of the Anderson impurity model show intermediate 5f⁵–5f⁶-valence ground state and delocalization of the 5f⁵ multiplet of the Pu atom 5f-shell in PuCoGa₅, and δ-Pu. The 5f-local magnetic moment is compensated by a moment formed in the surrounding cloud of conduction electrons. For PuCoGa₅ and δ-Pu the compensation is complete and the Anderson impurity ground state is a singlet. This can be important for analyses of the superconducting pairing mechanism in PuCoGa₅. It is likely that in PuCoGa₅ unconventional d-wave superconductivity is mediated by the 5f-states valence fluctuations, rather than antiferromagnetic fluctuations.     

VUV emission of Xe III levels excited by electron impact viaN 4,5 00 Auger transitions

Optical excitation functions were measured for Xenon emission lines. The Xe III 5s 5p ⁵ levels are excited in two different processes, by a direct two electron ejection and by a 4d ionization followed by an Auger decay. An emission line found at 1089.0 Å is excited by 4d ionization. This line is assigned to the Xe III transition 5s5p ^{5 1} P ⁰ —5s ⁰ 5p ^{6 1} S. The¹ S energy level amounts to 26.14 eV.